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  • 1.
    Wagner, Leopold
    et al.
    Vienna University of Technology, Austria.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    Ters, Thomas
    Vienna University of Technology, Austria.
    Fackler, Karin
    Vienna University of Technology, Austria.
    de Borst, Karin
    University of Glasgow, UK.
    A combined view on composition, molecular structure, and micromechanics of fungal degraded softwood2015Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 69, nr 4, 471-482 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fungal decay alters the composition, microstructure, and mechanical properties of wood cell walls. To understand better the structure-function relationships during fungal decay, selected annual rings of fungal deteriorated Scots pine sapwood were analyzed in terms of their composition, microstructure, and micromechanical properties. The datasets were acquired separately for earlywood and latewood concerning the S2 cell wall layer and the cell corner middle lamella (CCML) and analyzed by means of principal component analysis and partial least squares regression analysis. Links between cell wall stiffness and hardness and the composition and microstructure could be established. Increased mechanical properties in the CCML, as obtained by nanoindentation, were correlated to the degradation of pectins. In the S2 layer, the altered data were related to the degradation of hemicelluloses and lignin modification during fungal decay.

  • 2. Kortsalioudakis, Nathanail
    et al.
    Petrakis, Panagiotis
    Moustaizis, Stavros
    Voulgaridis, Elias
    Adamopoulos, Stergios
    Karastergiou, Sotirios
    Passialis, Costas
    An application of a laser drilling technique to fir and spruce wood specimens to improve their permeability2015Ingår i: Innovation in Woodworking Industry and Engineerings Design, ISSN 2367-6663, nr 1, 5-13 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, the application of a laser drilling technique on fir (Abies borisii regis) and spruce (Picea excelsa) wood and a new approach of improvement the wood permeability is investigated. This technique is focusing on increasing the permeability of wood after surface drilling by a high power laser source. The research was involving the establishment of an effective drilling pattern protocol, which will not substantially affect the mechanical strength of wood and to improve its permeability. All lateral surfaces of the wood specimens, 2 × 2 cm in cross section and 34 cm long, were drilled by laser to a depth of 4 mm (1/5 of specimen thickness) with two drilling patterns (distance between holes 10 × 10 mm and 10 × 20 mm). Preliminary results showed that laser drilling is a promising method for improvement of wood permeability without significant effect on its mechanical strength, and this is very important for an effective treatment of the refractory to impregnation fir and spruce wood.

  • 3.
    Rytter, Lars
    et al.
    The Forestry Research Institute of Sweden (Skogforsk).
    Andreassen, Kjell
    The Norwegian Forest and Landscape Institute, Norway.
    Bergh, Johan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Eko, Per-Magnus
    Swedish University of Agricultural Sciences.
    Gronholm, Tiia
    Finnish Environment Institute, Finland.
    Kilpelainen, Antti
    Finnish Environment Institute, Finland.
    Lazdina, Dagnija
    Latvian State Forest Research Institute “Silava”, Latvia.
    Muiste, Peeter
    Estonian University of Life Sciences, Estonia.
    Nord-Larsen, Thomas
    Copenhagen University, Denmark.
    Availability of Biomass for Energy Purposes in Nordic and Baltic Countries: Land Areas and Biomass Amounts2015Ingår i: Baltic Forestry, ISSN 1392-1355, E-ISSN 2029-9230, Vol. 21, nr 2, 375-390 s.Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    This review compiles information on the current state of the forests and analyses the potential of forest fuels for energy purposes in Denmark, Finland, Norway, Sweden, Estonia and Latvia. In these countries the forest area is 61 mill. ha, corresponding to 52% of the land areas, which is high in a European perspective where 38% of the land area is forest (EU-27). Although some forest areas are protected, 75-92% of the area can still be used for wood production. Further, substantial agriculture land areas may also be available for production of biomass for energy. Coniferous species dominate the forests in Finland, Norway and Sweden, while a more even distribution of conifers and deciduous species is found in Denmark, Estonia and Latvia. The total growing stock is around 7,400 mill. m(3) and the annual increment is estimated to about 275 mill. m(3) yr(-1) Annual growth currently exceeds annual harvest, leading to the conclusion that some of the difference may be used for energy purposes in the near future. The current potential for forest fuel resources was estimated to 230-410 TWh yr(-1) (830-1,480 PJ yr(-1)) for the countries included and forest fuels will thus be of utmost importance for the future energy supply in the area. A changing climate with larger standing volumes may affect the future growth positively and increase the potential harvest levels. Estimates from Finland, Sweden and Norway show an average growth increase of over 30% by the end of the century and substantially higher for specific regions. Wood is extensively used for energy purposes and the forests hold a large potential for increasing the production of renewable energy. The potential may be further increased in the future with increased fertilization, extended breeding for enhanced biomass production, larger cultivation areas and changes of tree species and management systems.

  • 4.
    Phiri, Darius
    et al.
    Univ Stellenbosch, South Africa.
    Ackerman, Pierre
    Univ Stellenbosch, South Africa.
    Wessels, Brand
    Univ Stellenbosch, South Africa.
    du Toit, Ben
    Univ Stellenbosch, South Africa.
    Johansson, Marie
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Säll, Harald
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Lundqvist, Sven-Olof
    Innventia AB, Wood & Fibre Measurement Lab, Stockholm.
    Seifert, Thomas
    Univ Stellenbosch, South Africa.
    Biomass equations for selected drought-tolerant eucalypts in South Africa2015Ingår i: Southern Forests, a journal of forest science, ISSN 2070-2620, E-ISSN 2070-2639, Vol. 77, nr 4, 255-262 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the water-scarce environment of South Africa, drought-tolerant eucalypt species have the potential to contribute to the timber and biomass resource. Biomass functions are a necessary prerequisite to predict yield and carbon sequestration. In this study preliminary biomass models for Eucalyptus cladocalyx, E. gomphocephala and E. grandis x E. camaldulensis from the dry West Coast of South Africa were developed. The study was based on 33 trees, which were destructively sampled for biomass components (branchwood, stems, bark and foliage). Simultaneous regression equations based on seemingly unrelated regression were fitted to estimate biomass while ensuring additivity. Models were of the classical allometric form, ln(Y) = a+x(1)ln(dbh)+x(2)ln(h), of which the best models explained between 70% and 98% of the variation of the predicted biomass quantities. A general model for the pooled data of all species showed a good fit as well as robust model behaviour. The average biomass proportions of the stemwood, bark, branches and foliage were 60%, 6%, 29% and 5%, respectively.

  • 5.
    Warren, Jeffrey M.
    et al.
    Oak Ridge National Laboratory, USA.
    Jensen, Anna M.
    Oak Ridge National Laboratory, USA.
    Medlyn, Belinda E.
    Macquarie University, Australia.
    Norby, Richard J.
    Oak Ridge National Laboratory, USA.
    Tissue, David T.
    University of Western Sydney, Australia.
    Carbon dioxide stimulation of photosynthesis in Liquidambar styraciflua is not sustained during a 12-year field experiment2015Ingår i: AoB Plants, ISSN 2041-2851, E-ISSN 2041-2851, Vol. 7, plu074Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Elevated atmospheric CO2 (eCO2) often increases photosynthetic CO2assimilation (A) in field studies of temperate tree species. However, there is evidence that A may decline through time due to biochemical and morphological acclimation, and environmental constraints. Indeed, at the free-air CO2 enrichment (FACE) study in Oak Ridge, Tennessee, A was increased in 12-year-old sweetgum trees following 2 years of ∼40 % enhancement of CO2A was re-assessed a decade later to determine if the initial enhancement of photosynthesis by eCO2 was sustained through time. Measurements were conducted at prevailing CO2 and temperature on detached, re-hydrated branches using a portable gas exchange system. Photosynthetic CO2 response curves (A versus the CO2 concentration in the intercellular air space (Ci); or ACi curves) were contrasted with earlier measurements using leaf photosynthesis model equations. Relationships between light-saturated photosynthesis (Asat), maximum electron transport rate (Jmax), maximum Rubisco activity (Vcmax), chlorophyll content and foliar nitrogen (N) were assessed. In 1999, Asat for eCO2treatments was 15.4 ± 0.8 μmol m−2 s−1, 22 % higher than aCO2treatments (P < 0.01). By 2009, Asat declined to <50 % of 1999 values, and there was no longer a significant effect of eCO2 (Asat = 6.9 or 5.7 ± 0.7 μmol m−2 s−1 for eCO2 or aCO2, respectively). In 1999, there was no treatment effect on area-based foliar N; however, by 2008, N content in eCO2 foliage was 17 % less than that in aCO2 foliage. Photosynthetic N-use efficiency (Asat : N) was greater in eCO2 in 1999 resulting in greaterAsat despite similar N content, but the enhanced efficiency in eCO2 trees was lost as foliar N declined to sub-optimal levels. There was no treatment difference in the declining linear relationships between Jmax or Vcmax with declining N, or in the ratio of Jmax : Vcmax through time. Results suggest that the initial enhancement of photosynthesis to elevated CO2 will not be sustained through time if N becomes limited.

  • 6.
    Blomqvist, Lars
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Berg, Sven
    Luleå University of Technology, Sweden.
    Sandberg, Dick
    Luleå University of Technology, Sweden.
    Chipless Machining: Challenges in Manufacture of Laminated Veneer Products2015Ingår i: Proceedings of the 22nd International Wood Machining Seminar, IWMS 22: Volume 1 - Oral Presentations / [ed] Roger Hernández and Claudia B. Cáceres, Quebec City, Canada: Université Laval , 2015, 155-164 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    A laminated veneer product (LVP) consists of veneers bonded together with adhesive under pressure into a predetermined shape and, in general, under increased temperature to shorten the curing time of the adhesive. The process is commonly used in furniture design to manufacture complex forms such as thin shells. In the industrial production of LVP and when the ready-for-use components are exposed to climate variations, rejection due to distortion of the laminates is a major problem. The shape stability depends on a variety of material and process parameters, and this study has focused on the influence of fibre deviation in a single veneer. Recent research on the shape stability of LVP and how distortion is influenced by various material and production parameters is presented. A finite-element model for LVP is introduced and the use of this model is exemplified by predicting the shape of a LVP with fibre distortion in a single veneer. The results show that it is possible to improve the shape stability of LVP if knowledge of various material and process parameters is implemented in the manufacturing process, and that a simulation based on a model of the wood material can be helpful in estimating the risk of an undesired deformation of the product.

  • 7.
    Nilsson, Bengt
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Nilsson, Daniel
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Thörnqvist, Thomas
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Distribution of logging residues at the clear-felled site after fuel adapted logging operations2015Ingår i: Papers of the 23rd European Biomass Conference: Setting the course for a biobased economyExtracted from the Proceedings of the International Conference held in Viennna, Asutria1-4 June 2015 / [ed] Obernberger I, Baxter D, Grassi A, Helm P, ETA-Florence Renewable Energies , 2015, 270-272 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    During extraction of logging residues previous studies in Sweden have shown that up to 50% of the available logging residues will not reach the energy-conversion site. The remaining potential of the logging residues are therefore lost by handling either at the clear-felled site, during transportation or due to decomposition. An outtake of 100% is not possible or desired, since the Swedish Forest Agency recommends that at least 20% of the logging residues should be left at the clear-felled site after a fuel adapted logging operation. In this study the losses at the clear-felled area is examined by studying the distribution of the remaining logging residues under and between the harvester heaps as well amount of logging residues that are left at the roadside landing after comminution. The results show that most of the reaming logging residues are well distributed at the clear-felled area between the harvester heaps. Additional logging residues are left at the clear-felled area since the forwarder cannot gather all logging residues from under the harvester heaps. In addition to this a not insignificant amount of logging residues are left at the roadside landing.

  • 8.
    Nilsson, Bengt
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Nilsson, Daniel
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Thörnqvist, Thomas
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Distributions and Losses of Logging Residues at Clear-Felled Areas during Extraction for Bioenergy: Comparing Dried- and Fresh-Stacked Method2015Ingår i: Forests, ISSN 1999-4907, E-ISSN 1999-4907, Vol. 6, nr 11, 4212-4227 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is well known that a large proportion of available logging residues intended for extraction will not reach the energy-conversion industry, because some are lost during transportation or left on the clear-felled area. However, there is little understanding of where logging residue losses occur in the supply chain. In this study, the distribution of logging residues for two methods (dried- and fresh-stacked method) to extract logging residues were studied in one clear-felled area. In addition, residue fractions were examined in a detailed comparison. Even though the fresh-stacked method left somewhat more logging residues at the clear-felled area, the differences are small between the methods. Approximately 30% of the total amount of logging residues was left behind between the harvester heaps, with an additional 10%-15% under these heaps and approximately 2%-3% beneath the windrows. The final product that was delivered to the energy-conversion industry was very similar, regardless of the extraction method used. The delivered chipped logging residues had moisture contents of 37% and 36% following fresh- and dried-stacked methods respectively, and in both cases the needle content in the processed logging residues was approximately 10%. However, the total amount of fine fractions (needles and fines) was slightly higher following dried-stacking.

  • 9.
    Hosseinpourpia, Reza
    et al.
    Georg-August-University Göttingen, Germany.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Mai, Carsten
    Georg-August-University Göttingen, Germany.
    Dynamic water vapour sorption properties and dimensional stability of thermally and acid-treated Scots pine (Pinus sylvestris L.)2015Ingår i: 69th Forest Products Society (FPS) International Convention, June 10-12, Atlanta, GA, Forest Products Society , 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    In order to accelerate the thermal modification process, Scots pine sapwood samples were subjected to two types of treatments. One group of samples was impregnated with water and exposed to 220oC and the second group was initially treated with low concentration of acids (1 mol l-1 AlCl3 and a mixture of 0.5 mol l-1 H2SO4 and 1 mol l-1 AlCl3), and then heated at different temperatures (180 and 120oC) to achieve comparable mass loss (ML) levels. The water vapour sorption isotherms of the thermally and acid-treated wood samples were determined using a dynamic vapour sorption (DVS) apparatus. Increasing the temperature in both thermally and acid-treated samples resulted in ML attributable to hemicelluloses degradation. As a result thereof, dimensional stability and reduction in the hygroscopicity of wood were observed. Acid-treated samples heated at lower temperature exhibited similar water sorption behaviour as water-treated samples subjected to considerably higher temperature. The sorption data were analysed using the Hailwood-Horrobin (H-H) and excess surface work (ESW) models. The data indicated that the monolayer and polylayer sorption were reduced by the acid and thermal treatments, but acid treatment reduced the monolyer sorption stronger than the thermal. The effect of thermal and acid treatments on the flexibility of the cell wall matrix could not be fully distinguished.

  • 10.
    Hosseinpourpia, Reza
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Göttingen university, Germany.
    Mai, Carsten
    Dynamic water vapour sorption properties of wood cell wall polymer constituents2015Ingår i: COST FP1303 (Performance of bio-based building materials) / [ed] Dennis Jones, Christian Brischke, Jaan Kers, Triinu Poltimäe and Joachim Schmid, SP Technical Research Institute of Sweden , 2015, 42-44 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Lignin, cellulose and hemicelluloses have main roles on swelling and shrinkage of wood products. Interaction of these components with moisture has an important effect on market-friendly when the wood is subjected to the outside utilizations. In the heterogeneous structure of wood, sorption and desorption are occurred in different stages and it calls hysteresis. Hysteresis is a characteristic result from a moisture/temperature/time-dependent, slow, non-equilibrium, swelling-related conformational change, which is facilitated by increasing free volume and mobility in a polymer that is being plasticized during sorption that usually progresses through the stage of water clustering (Reina et al. 2001). Cell wall polymers of wood have a different behavior in the face of moisture in terms of sorption, desorption and hysteresis (Engelund et al. 2013).

    In order to better comprehension of the effect of cell wall material such as lignin, cellulose and hemicelluloses, Scots pine micro-veneers were subjected to hydrolysis with sulphuric acid or delignification with acidic sodium chlorite, as previously described (Klüppel and Mai 2012). Then the hemicelluloses were isolated from the delignified veneers according to the chloride method. The commercial lignin was also used after dialysis tubing. The water adsorption and desorption mechanism of delignified and hydrolysed veneers as well as cell wall polymers such as cellulose, hemicelluloses and lignin were determined using a dynamic vapour sorption (DVS) apparatus.

    The hydrolysed veneers were resulted in obviously lower moisture content in adsorption and desorption processes with increasing the relative humidity (RH) (Fig. 1a). While, delignified veneers showed slightly higher moisture content compared to control with increasing the ambient moisture until 70% RH and then considerably higher until 95% RH. Control specimens shown higher hysteresis than hydrolysed veneers and also higher hysteresis than delignified veneers after hygroscopic range (Fig. 1b). Moisture content of cell wall constituents in various relative humidity exhibited the higher moisture sorption and desorption of cellulose than lignin, however, hemicelluloses illustrated the significantly higher moisture content than other two cell wall polymers which might be attributed to the softening of hemicelluloses in higher relative humidity (Fig. 2a,b,c). Lignin showed higher hysteresis than cellulose in different relative humidity. Hemicellulose demonstrated the relatively low hysteresis until 50% RH, and with increasing the ambient pressure from 60% RH the hemicelluloses exhibited the extremely higher hysteresis than other cell wall polymers.

  • 11.
    Schauerte, Tobias
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för maskinteknik (MT).
    Editorial2015Ingår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 10, nr 3, 215- s.Artikel i tidskrift (Övrigt vetenskapligt)
  • 12.
    Wagner, Leopold
    et al.
    Vienna University of Technology, Austria.
    Bos, Clemence
    Vienna University of Technology, Austria ; Institute for applied materials, Germany.
    Bader, Thomas K.
    Vienna University of Technology, Austria.
    de Borst, Karin
    University of Glasgow, UK.
    Effect of Water on the Mechanical Properties of Wood Cell Walls: Results of a Nanoindentation Study2015Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 10, nr 3Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The paper presents a nanoindentation study on five different wood species in which the elastic and creep properties of the S2 cell wall layer and the middle lamella were determined. Measurements were carried out at relative humidities (RH) ranging from 10 to 80% as well as underwater. Indentation moduli were found to decrease by about a third in the S2 layer and by about half in the middle lamella between RH of 10 and 80%. Hardness dropped by 50 to 60% in this humidity range in both the S2 layer and the middle lamella. Creep parameters were almost constant up to a relative humidity of 40%, but they increased considerably at higher RH. The most pronounced change of reduced moduli and creep properties occurred between 60 and 80% RH, which is consistent with the expected softening of hemicellulose and amorphous parts of cellulose in this humidity region. Immersion into water resulted in a further decrease of the reduced moduli to about 20 to 30% of their values at 10% RH and to only about 10 to 20% for the hardness. This can be explained by additional softening of the less ordered regions of cellulose.

  • 13.
    Bonarski, Jan T.
    et al.
    Polish Academy of Sciences, Poland.
    Kifetew, Girma
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Olek, Wieslaw
    Poznań University of Life Sciences, Poland.
    Effects of cell wall ultrastructure on the transverseshrinkage anisotropy of Scots pine wood2015Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 69, nr 4, 501-507 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A hypothesis for explaining the differential anisotropicshrinkage behavior of wood has been proposed,and it was based on the differences in the cell wall ultrastructure.The starting point of the consideration is thatwood shrinkage is governed by its chemical composition,ultrastructure, and gross anatomy. It is also well knownthat the transverse shrinkage anisotropy of earlywood(EW) is more pronounced than that of the latewood (LW).In the paper, the cell wall ultrastructure and shrinkageanisotropy has been related to each other, and to thispurpose, a set of crystallographic texture descriptorswas applied. The descriptors are based on X-ray diffraction(XRD) experiments conducted on matched EW samplesfrom different growth rings of Scots pine. The rangeof the microfibril angle (MFA) was identified. The ratio ofthe maxima of inverse pole figures (IPFs) of both the tangential(T) and radial (R) directions was determined. Theratios quantify the inhomogeneity of the spatial arrangementof the ordered areas. The results of the study clearlyindicate that the transverse shrinkage of wood is governedmostly by a specific ultrastructural organization of moderatelyorganized cell wall compounds.

  • 14. Voulgaridis, Elias
    et al.
    Adamopoulos, Stergios
    Karastergiou, Sotirios
    Passialis, Costas
    Koutsianitis, Dimitrios
    Kortsalioudakis, Nathanail
    Petrakis, Panagiotis
    Moustaizis, Stavros
    Effects of laser drilling on mechanical properties and impregnability of fir and spruce wood2015Ingår i: Innovation in Woodworking Industry and Engineering Design, ISSN 2367-6663, nr 1, 14-22 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fir (Abies borisii regis) and spruce (Picea excelsa) wood specimens, 2 × 2 cm in cross section and 34 cm long, were prepared with true radial and tangential surfaces. All lateral surfaces of the specimens were drilled by laser to a depth of 4 mm (1/5 of specimen thickness) with two drilling patterns (distance between holes 1 × 1 cm and 1 × 2 cm). ). After drilling, the mechanical strength of wood (MOE, MOR, axial compression, toughness) was determined and compared with non-drilled controls. MOE was not affected by the laser drilling, MOR was significantly increased, axial compression was increased and toughness was decreased but not significantly. The overall results imply that strength properties do not decline by the laser drilling. Furthermore, wood specimens were impregnated with rape oil and CCB preservatives by applying vacuum (0.6 mmHg) and pressure (1,5 bars) for 15 minutes and 30 minutes, respectively. The results showed that both drilling patterns improved the retention and penetration of preservatives in fir and spruce wood specimens and, thus, are encouraging for further evaluating the drilling effects on the liquid permeability of these refractory to impregnation species. This effect was more pronounced in fir than in spruce wood.

  • 15.
    Bastani, Alireza
    et al.
    Georg-August-University Göttingen, Germany.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Militz, Holger
    Georg-August-University Göttingen, Germany.
    Gross adhesive penetration in furfurylated, N-methylol melamine-modified and heat-treated wood examined by fluorescence microscopy2015Ingår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 73, nr 5, 635-642 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study investigated the radial penetration of three conventional cold-set wood adhesives [emulsion polymer isocyanate (EPI), poly (vinyl acetate) (PVAc), one-component polyurethane (PU)] into various degrees of furfurylated and N-methylol melamine-modified (NMM) Scots pine, and heat-treated Scots pine and beech based on measurements of effective (EP) and maximum penetration (MP) from microscopic observations. EP of EPI adhesive decreased after modification with higher concentration of furfuryl alcohol while an improved penetration was recorded for PVAc into furfurylated wood. A deeper penetration was observed for all adhesives into wood treated with lower concentration of furfuryl alcohol. The EP of EPI and PU adhesives reduced after NMM treatment but it increased in the case of PVAc. In spite of reduction of EP of PU after NMM treatment, it represented a deeper penetration among all adhesives possibly due to its lower molecular weight. For Scots pine, increasing the treatment temperature improved EP of all adhesives while for beech, the EP of PU and PVAc increased largely in the case of samples treated at 195 °C. Visual analysis of fluorescence microscopy pictures provided more detailed information on modality of penetration. The results are useful for understanding the interaction among common adhesives and modified materials, and can be used in future research to explain the bonding behavior of modified wood.

  • 16.
    Eliasson, Lars
    et al.
    Skogforsk.
    Nilsson, Bengt
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Hyggeslagring av grot2015Övrigt (Övrigt vetenskapligt)
  • 17.
    Subramanian, Narayanan
    et al.
    Swedish University of Agricultural Sciences.
    Karlsson, Per Erik
    Swedish University of Agricultural Sciences.
    Bergh, Johan
    Swedish University of Agricultural Sciences.
    Nilsson, Urban
    Swedish University of Agricultural Sciences.
    Impact of Ozone on Sequestration of Carbon by Swedish Forests under a Changing Climate: A Modeling Study2015Ingår i: Forest Science, ISSN 0015-749X, E-ISSN 1938-3738, Vol. 61, nr 3, 445-457 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The annual growth rates in Swedish forests are higher than the annual harvest rates, and this has resulted in high rates of carbon sequestration in the Swedish forestry sector. Any factor that tends to reduce growth rates also has the potential to reduce forest carbon sequestration rates, and ozone may be one such factor. The aim of this study was to estimate to what extent the occurrence of elevated tropospheric ozone concentrations can negatively affect carbon sequestration by Swedish forest ecosystems. The net primary production (NPP) of Swedish forests was simulated, using the 3-PG model, for representative forest stands in six different geographical zones across Sweden, with and without assumed negative impacts of ozone. Ozone impacts were derived from dose-response relationships, calculated from open-top chamber experiments with young trees. The results of the 3-PG simulations showed that the NPP was generally higher in the A2 and B2 Intergovernmental Panel on Climate Change (IPCC) future climate scenarios, as compared to the current climate, for all tree species and in all geographical zones across Sweden. Biomass production was reduced by 4.3‐15.5% for conifers (Norway spruce (Picea abies L) and Scots pine (Pinus sylvestris L) and by 1.4‐4.3% for birch (Betula pendula Roth and Betula pubescence Ehrh) under ambient ozone conditions as compared to the preindustrial ozone level. The greatest reduction in biomass was found in southern Sweden. Biomass was reduced by similar percentage value in future climate scenarios as that in the current climate.

  • 18.
    Schauerte, Tobias
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för maskinteknik (MT).
    Lindblad, Fredrik
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för maskinteknik (MT).
    Improving Profitability by Improving the Material and Production Flow: 3 case studies of Swedish Wooden Single-Family House Producers2015Ingår i: Forum Wood Building Nordic Växjö 2015: Competition and competence: how can we reach a higher level?, Linnaeus Univeristy , 2015Konferensbidrag (Övrigt vetenskapligt)
  • 19.
    Esteban, Luis García
    et al.
    Ciudad Universitaria, Spain.
    Simón, Cristina
    Ciudad Universitaria, Spain.
    Fernández, Francisco García
    Ciudad Universitaria, Spain.
    Palacios, Paloma de
    Ciudad Universitaria, Spain.
    Martín-Sampedro, Raquel
    Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Spain.
    Eugenio, María Eugenia
    Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Spain.
    Hosseinpourpia, Reza
    Georg August University, Germany.
    Juvenile and mature wood of Abies pinsapoBoissie: sorption and thermodynamic properties2015Ingår i: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 49, nr 4, 725-738 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For industrial processes, it is important to study the hygroscopicity and thermodynamic properties of juvenile and mature wood. Samples of Abies pinsapo Boiss. collected in the natural areas of the species in Spain were used to study these properties in both types of wood. The equilibrium moisture contents were obtained, and the 15, 35 and 50 °C isotherms were plotted following the Guggenheim–Anderson–Boer–Dent model. The thermodynamic parameters were calculated using the integration method of the Clausius–Clapeyron equation. Chemical analyses, infrared spectra and X-ray diffractograms were applied to assess chemical modifications and possible changes in the cell wall structure. The chemical composition of the mature wood shows a decrease in the lignin and hemicelluloses content and an increase in the extracts and α-cellulose. The sorption isotherms for the three temperatures studied are higher in the mature wood than in the juvenile wood. Causes of this include the higher content of α-cellulose, the higher crystallinity index and the shorter crystallite length in the mature wood. No difference was found between the juvenile and mature wood in relation to the point of inflexion where the multilayer starts to predominate over the monolayer (approximately 30 %). In terms of the thermodynamic properties, the heat involved is greater in desorption than in adsorption, and more heat is involved in the mature wood than in the juvenile wood.

  • 20.
    Kumar, Anuj
    et al.
    Czech Technical University in Prague, Czech Republic.
    Petrič, Marko
    University of Ljubljana, Slovenia.
    Kričej, Borut
    University of Ljubljana, Slovenia.
    Žigon, Jure
    University of Ljubljana, Slovenia.
    Tywoniak, Jan
    Czech Technical University in Prague, Czech Republic.
    Petr, Hajek
    Czech Technical University in Prague, Czech Republic.
    Škapin, Andrijana Sever
    Slovenian National Building and Civil Engineering Institute, Slovenia.
    Pavlič, Matjaž
    University of Ljubljana, Slovenia.
    Liquefied-Wood-Based Polyurethane–Nanosilica Hybrid Coatings and Hydrophobization by Self-Assembled Monolayers of Orthotrichlorosilane (OTS)2015Ingår i: ACS Sustainable Chemistry & Engineering, ISSN 2168-0485, Vol. 3, nr 10, 2533-2541 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have produced hybrid liquefied-wood-based polyurethane (LW-PU) and LW-PU/nanosilica hybrid coatings for wood substrates. The prepared hybrid polyurethane coatings were hydrophobized by self-assembled monolayers of orthotrichlorosilane (OTS) via a sol–gel dipping process. The nanosilica addition into the LW-PU system enhanced the physical properties of coatings like surface hardness and stability toward cold liquids. The OTS hydrophobized coatings were characterized by Fourier transforms infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and thermogravimetric analysis (TGA). The surface became hydrophobic as the contact angle (CA) for the water droplet on a modified hybrid coating was ∼115° and very stable. The FTIR, SEM, and EDS analysis confirmed the formation of OTS monolayers on hybrid coatings.

  • 21.
    Wessels, CB
    et al.
    University of Stellenbosch, South Africa.
    Crafford, PL
    University of Stellenbosch, South Africa .
    du Toit, B
    University of Stellenbosch, South Africa.
    Grahn, T
    Innventia, Sweden.
    Johansson, Marie
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Lundqvist, S-O
    Innventia, Sweden.
    Säll, Harald
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Seifert, T
    Univesity of Stellenbosch, South Africa.
    Lumber properties of three drought tolerant eucalyptus species grown in arid regions of south africa2015Ingår i: IUFRO Symposium: Silviculture and Management of Dryland Forests,, 2015Konferensbidrag (Övrigt vetenskapligt)
  • 22.
    Adamopoulos, Stergios
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Foti, Dafni
    Aristotle University of Thessaloniki, Greece.
    Voulgaridis, Elias
    Aristotle University of Thessaloniki, Greece.
    Passialis, Costas
    Aristotle University of Thessaloniki, Greece.
    Manufacturing and properties of gypsum-based products with recovered wood and rubber materials2015Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 10, nr 3, 5573-5585 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The experimental production of gypsum-based products (cylindrical samples, solid bricks) using different fractions of wood chips and rubber particles was studied. Recovered rubber and wood materials were mixed with gypsum and water in various proportions to fabricate gypsum-wood and gypsum-rubber cylindrical samples and standard solid bricks with six holes using appropriate molds. It was shown that to manufacture gypsum-wood and gypsum-rubber products with good mechanical strength, coarse fractions of wood and rubber should be used, but the proportion of wood or rubber should not exceed 25%. No thermal conductivity differences were found between the wood-and rubber-type of gypsum products, and particle size and material proportion had no effect. Samples with fine wood and rubber particles present at a lower proportion (25%) exhibited similar sound absorption behavior. The solid bricks had slightly higher strength when loaded at the large surface of their lateral upper side than when loaded at the small surface. The bricks provided better thermal insulation than both the extruded and pressed house bricks but lower than that of insulating bricks. The emission of volatile organic compounds out of the bricks was at an acceptable level according to regulations for construction products.

  • 23. Balea, A
    et al.
    Blanco, A
    Fuente, H
    Concepción, M
    Negro, C
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Hosseinpourpia, Reza
    Mai, C
    Tubek-Lindblom, A
    Hansen, P
    Morphology, properties and recyclability of modified fibres and papers with different chemicals at laboratory and pilot plant trials2015Ingår i: 46th Congresso Annuale Aticelca, May 28-29, Sestri Levante-Genova, Italy, Aticelca , 2015, 23-31 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Fibre+ (2012-2015) is a European project aiming to develop potential treatments for recovered fibre modification capable of improving the recyclability and the properties of recycled papers. This study reports on the results on fibre morphology, paper properties and recyclability of fibres and papers modified with different chemicals and approaches from both laboratory and pilot plant trials. Sixteen modification chemical agents were studied in a set of laboratory trials. The raw material used was 100% recycled paper grade from old corrugated board containers (OCC). The laboratory analysis to evaluate the effectiveness of fibre modifications treatments included FBRM for pre-screening of chemicals, preparation of laboratory control and modified handsheets to a target grammage of 80 g/m2, and measurement of the fibre morphology, recyclability and mechanical and physical properties of the modified handsheets. Based on the results of laboratory testing, Fibre+ modifications pilot plant trials were carried out at a FEX paper machine. Furthermore the effect of the better dispersion of the cPAM using an ECOWIRL was studied. The overall laboratory and pilot plant results were promising for further implementation of the Fibre+ modifications at industrial scale and projection of improvements of fibre and paper properties on the performance of packaging products thereof

  • 24.
    Jensen, Anna M.
    et al.
    Oak Ridge National Laboratory, USA.
    Warren, Jeffrey M.
    Oak Ridge National Laboratory, USA.
    Hanson, Paul
    Oak Ridge National Laboratory, USA.
    Childs, Joanne
    Oak Ridge National Laboratory, USA.
    Wullschleger, Stan
    Oak Ridge National Laboratory, USA.
    Needle age and season influence photosynthetic temperature response and total annual carbon uptake in mature Picea mariana trees2015Ingår i: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 116, nr 5, 821-832 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background, Aims and Methods; The carbon (C) balance of boreal terrestrial ecosystems is sensitive to increasing temperature, but the direction and thresholds of responses are uncertain. Annual C uptake in Picea and other evergreen boreal conifers is dependent on seasonal- and cohort-specific photosynthetic and respiratory temperature response functions. To assess the physiological significance of maintaining multiple foliar cohorts we measured photosynthetic capacity, foliar respiration (Rd), and leaf biochemistry and morphology of mature Picea mariana trees within an ombrotrophic bog ecosystem in Minnesota, USA. Results were applied to a simple model of canopy photosynthesis to simulate annual C uptake by cohort age under ambient and elevated temperature scenarios.

    Key Results; Temperature responses of key photosynthetic parameters (i.e., light-saturated rate of CO2 assimilation (Asat), rate of Rubisco carboxylation (Vcmax), electron transport rate (Jmax)) were dependent on season and generally less responsive in the developing current-year (Y0) needles compared to one-year-old (Y1) or two-year-old (Y2) foliage. Temperature optimums ranged from 18.7 - 23.7, 31.3 - 38.3 and 28.7 - 36.7°C for Asat, Vcmax and Jmax, respectively. Foliar cohorts differed in their morphology and photosynthetic capacity, which resulted in 64% of modeled annual stand C uptake from Y1&2 cohorts (LAI 0.67 m2 m-2) and just 36% from the Y0 cohorts (LAI 0.52 m2 m-2). Under warmer climate change scenarios, the contribution of Y0 cohorts was even less; e.g., 31% of annual C uptake for a modeled 9°C rise in mean summer temperatures. Results suggest that net annual C uptake by P. mariana could increase under elevated temperature, and become more dependent on older foliar cohorts.

    Conclusions; Collectively, these results illustrate the physiological and ecological significance of different foliar cohorts, and indicate the need for seasonal- and cohort-specific model parameterization when estimating C uptake capacity of boreal forest ecosystems under ambient or future temperature scenarios.

  • 25.
    Bahr, Adam
    et al.
    Lund University, Sweden.
    Ellström, Magnus
    Lund University, Sweden.
    Bergh, Johan
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Wallander, Håkan
    Lund University, Sweden.
    Nitrogen leaching and ectomycorrhizal nitrogen retention capacity in a Norway spruce forest fertilized with nitrogen and phosphorus2015Ingår i: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 390, nr 1-2, 323-335 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aims

    To estimate the production of external ectomycorrhizal mycelia (EMM) in Norway spruce forests with varying nitrogen (N) and phosphorus (P) levels, and to relate this to the N retention capacity of ectomycorrhizal fungi (EMF) and N leaching.

    Methods

    Seasonal changes in EMF production (in ingrowth mesh bags) and soil water N (in suction lysimeters) were analyzed after fertilization with N or N combined with P. The EMF N retention capacity was estimated by the addition of isotopically labeled N to the mesh bags.

    Results

    No relationship was found between the seasonal variation in EMF growth and N leakage from the soil. However, in the mesh bags, the total assimilation of 15N by EMF was almost halved by N fertilization, while twice as much 15N leached through.

    Conclusions

    We found a high specific N assimilation capacity per unit weight of EMF mycelia. This was unaffected by N fertilization, but the total assimilation of N by EMF was drastically reduced due to reduced production of EMM. However, N-retaining processes other than N assimilation by EMF must be taken into account to explain the losses of N after fertilization.

  • 26.
    Pearson, Hamish
    et al.
    New Zealand Forest Research Institute (Scion), New Zealand.
    Ormarsson, Sigurdur
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggteknik (BY).
    Gabbitas, Brian
    University of Waikato, New Zealand.
    Nonlinear tensile creep behavior of radiata pineat elevated temperatures and different moisturecontents2015Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 69, nr 7, 915-923 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Tensile wood creep has not been measured previouslyin the temperature region 135°C – 150°C for a rangeof moisture content (MC) up to fiber saturation point dueto equipment and measurement challenges. Yet this is theregion where the most dramatic softening effects can beobserved. The aim of this study was to develop specializedequipment to measure tensile solid wood creep over70°C – 150° C for a range of MC and loads. Creep displacementwas successfully able to be isolated from elasticand mechanosorptive strains and statistically modeledby regression analysis. This proved more accurate thancomplex series expansions consisting of spring- and dashpot-type components. The best creep displacement relationshipwas a power law with a strain root mean squareerror of 0.28%. The amplitude of the power law was nonlinearwith respect to stress and temperature and changedby a stress factor of up to 0.9 for a stress of up to 1.2 MPaand by a temperature factor 1.2 – 6.3 over the investigatedrange. The creep relationship provides a valuable tool forpredicting time-dependent distortion and internal stressof wood during drying or thermohygromechanical modificationbelow 150°C.

  • 27.
    Nilsson, Daniel
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Nilsson, Bengt
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Thörnqvist, Thomas
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Nutrient removal after whole-tree harvesting with the traditional Swedish dried-stacked method for removal of logging residues2015Ingår i: Papers of the 23rd European Biomass Conference: Setting the course for a biobased economyExtracted from the Proceedings of the International Conference held in Viennna, Asutria1-4 June 2015 / [ed] Obernberger I, Baxter D, Grassi A, Helm P, ETA-Florence Renewable Energies , 2015, 9-13 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Bioenergy from logging residues is an important contributor to Swedish energy supplies. Logging residues where long defined and regarded as the unmerchantable aboveground biomass left behind in the clear-felled area, consisting of branches, tops and small trees that are gathered after the round wood harvest, but logging residues are nowadays regarded as a third assortment next to timber and pulpwood with high economic value. However long-term experiments on removal of logging residues from Norway spruce (Picea abies (L.)Karst) stands have shown both growth reductions and growth increase in the next generation, because of decreasing amounts of nutrients. So an increased removal of logging residues requires some sort of compensation of nutrients. Therefore it is of importance to investigate how much nutrients that is removed from the stand after whole-tree harvesting.

    In this study the removal of the nutrients nitrogen (N), phosphorus (P), calcium (Ca), potassium (K) and magnesium (Mg) have been investigated by laboratory analysis of the nutrients together with the actual removal of stemwood, bark and logging residues. The study has also investigated the distribution of nutrients at the clear-felled area.

    The results show that approximately half of the total nutrient removed in whole tree harvesting is done with the removal of stemwood and bark. The results also show that approximately 30% of the total amount of nutrients is left at the clear-felled area.

  • 28.
    Blomqvist, Lars
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Shape stability of laminated veneer products: a review – defining and achieving shape stability2015Ingår i: International Wood Products Journal, ISSN 2042-6445, Vol. 6, nr 2, 89-95 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Laminated veneer products (LVPs) consist of veneers bonded together with an adhesive into a predetermined shape. Deviation from the intended shape is a problem for both manufacturers and customers of the final products. The shape stability of LVP depends on a variety of material and process parameters, and this review identifies several important factors that influence shape stability, the purpose being to find ways of decreasing distortion and improving shape stability so that product quality can be improved.

    The review ends to the following statements:

    The fibre orientation of the veneer strongly influences the shape stability of LVP. The products can show considerable distortion (particularly twist) if the fibre orientation of the veneer is oriented in an unsuitable way in the assembly before moulding.

    The effect of fibre orientation on shape stability can be very small directly after moulding, but it can increase considerably when the moulded product is subjected to a change in moisture content (MC). In general, a change in moisture leads to distortion. Moisture changes alone, however, result in a controlled distortion.

    The orientation of the loose and tight sides of the veneers in LVP affects the shape stability.

    An asymmetrical construction, coupled with different levels of moisture in the different veneers in an assembly before moulding, will result in poor shape stability of the product.

    The choice of wood species affects shape stability. Beech shows more distortion and poorer shape stability than birch.

    Based on existing knowledge to produce shape-stable LVP, the veneers should be conditioned to uniform MC and sorted with regard to fibre orientation and loose or tight side of the veneer before bonding. End-user climates should govern the veneers’ MC and added moisture from the adhesive during the process. Straight grain veneers and symmetry should always be sought.

    This review reveals several areas that need to be further clarified in order to achieve shape-stable LVP, for example the influence of adhesive, the distribution of pressure, temperature, stresses and strains during moulding and the development of numerical methods to better predict the final shape.

  • 29.
    Lars, Eliasson
    et al.
    Skogforsk.
    Nilsson, Bengt
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Skotning av grot direkt efteravverkning eller efter hyggeslagring: Effekter på näringsuttag, barravfall och fukthalt2015Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Sedan 1980-talet har rekommendationen varit att grot ska hyggeslagras under en sommar för att torka och ”barra av”. Torkningen ökar det effektiva värmevärdet och därigenom det ekonomiska värdet för den levererade mängden grot samt minskar uttaget av näringsämnen, vilket kan påverka skogsproduktionen. Hyggeslagring innebär samtidigt att grotskotningen måste utföras av en annan maskin än den som skotade rundvirket, vilket medför en extra maskinflytt som i sin tur ökar kostnaden för grotuttaget. Att grotskotningen koncentreras till barmarksperioden innebär att markberedning inte kan utföras under sommaren efter avverkningen, eftersom grothögarna finns kvar på hygget. Intresset för att skota groten direkt efter avverkning och torka den i en välta vid väg har ökat, då det ses som ett sätt att undvika dessa nackdelar.

    En genomgång av befintlig litteratur har genomförts för att ge en översikt av effekterna av dessa två uttagsstrategier för grot:

    - Skotning av grot till välta vid väg direkt efter avverkning.

    - Hyggeslagring av grot under en sommar innan grotskotning till välta vid väg.

     Litteraturstudien visar att:

    - Oavsett uttagsstrategi så blir mer än 20 procent av groten kvar på hygget.

    - Hyggeslagring av groten är ingen garant för att barren faller av och näring utlakas.

    - Hyggeslagrad grot är inte torrare än vältlagrad vid leverans.

    - De eventuella effekter som valet av uttagstrategi har på den framtida tillväxten bör vara mindre än det man kan se i försöken med helträdsuttag.

    - Skotning av färsk grot frigör hygget för markberedning och återplantering redan första sommaren efter avverkning, d.v.s. minst ett år tidigare än om groten skall hyggeslagras.

  • 30.
    Säll, Harald
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Spiral grain in trees from drought tolerant Eucalyptus species grown on dry land on the west coast of South Africa2015Ingår i: Collection of Extended abstractsfor the International Symposium: Silviculture and Management of Dryland Forests, Stellenbosch, South Africa,16-19 March 2015, Stellenbosch University , 2015, 87-89 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this project titled “Evaluation of drought resistant tree species to alleviate poverty in arid regions of South Africa” trees from a 20-year old field trial from two sites on the dry west coast area of South Africa were recently evaluated for growth characteristics. The three most promising Eucalyptus species, namely E. gomphocephala, E. cladocalyx and E. grandis × camaldulensis hybrid, for growth characteristics were selected for further evaluation. The objective of the study reported was to investigate between species variability of selected physical and processing properties determining the suitability of these three species for lumber production. It will also be useful for informing tree breeders and silviculturists to identify which properties need improvement through breeding selection or forest management strategies. And in the future results can hopefully be used for selection of species for small farm plantations which may be processed and sold to generate income.

    One of most common reasons for a customer to avoid using wood is the lack of shape stability. There is a clear connection between spiral growth and how twisted the sawn timber will be when it is dried. Depending on the log diameter a grain angle over 3 to 5 degrees will produce sawn wood that will be pronounced to twist. In older softwood trees, the cracks lean mostly to the right. This means that the grain angle is right handed, and the visible cracks create a spiral in an anti-clockwise direction, looking from the base to the top of the tree (Figure 1). In spruce trees, however, the grain angle close to the pith is left-handed, which means that the fibres follow a clockwise spiral up the trunk (Harris 1989).

  • 31.
    Hosseinpourpia, Reza
    et al.
    Georg August University Göttingen, Germany.
    Adamopoulos, Stergios
    Technological Educational Institute of Thessaly, Greece.
    Mai, Carsten
    Georg August University Göttingen, Germany.
    Tensile strength of handsheets from recovered fibers treated with N-methylol melamine and 1,3-dimethylol-4,5-dihydroxyethyleneurea2015Ingår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 132, nr 3, 41290Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The main objective of this study was to assess the effect of two amino resins, N-methylol melamine (NMM) and 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU), on the intrafiber and interfiber strengths and water absorption of two types of waste paper categories, office paper (OP), and old corrugated containers (OCCs). The tensile strength of individual fibers measured at zero span was reduced by increases in the resin concentrations. The dry tensile strengths of the recovered handsheets measured at a finite span were enhanced with increases in the weight percentage gain of the resins. The increasing of the resin concentration also significantly improved the intrabonding of the OP and OCCs in moist measuring conditions. The water absorption of the handsheets considerably decreased at the higher concentration of the thermosetting resins, especially with NMM. The results are promising for the use of NMM- and DMDHEU-treated recovered fibers as an alternative fiber resource for the production of laminated paper and also for the use of DMDHEU as a new N-methylol compound for laminated paper.

  • 32.
    Adamopoulos, Stergios
    et al.
    Technological Educational Institute of Thessaly, Greece.
    Hosseinpourpia, Reza
    Georg-August-University Göttingen, Germany.
    Mai, Carsten
    Georg-August-University Göttingen, Germany.
    Tensile strength of handsheets prepared with macerated fibres from solid wood modified with cross-linking agents2015Ingår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 69, nr 8, 959-966 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study was conducted to explain the tensile strength loss of wood due to the modification with 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) and glutaraldehyde (GA). Modified and control wood blocks were macerated to deliberate fibres, and handsheets were produced thereof. The nitrogen content of the fibres indicated that maceration removed the major proportions of DMDHEU. The stability of GA in wood during maceration was not assessed. Tensile strength determined at zero span (z-strength) and finite span (f-strength) was equal for the handsheets from DMDHEU-modified fibres and the control handsheets. The microscopic appearance of the tested finite-span paper strips from DMDHEU-modified fibres mainly indicated interfibre failure and did not differ from the fibre fracture mode of the control handsheets. In contrast, the z-strength of the handsheets from GA-modified fibres was lower than that of controls and decreased with increasing content of GA in the initial modified wood. The f-strength behaviour of the handsheets from GA-modified fibres was the opposite: it was higher than that of controls and increased with increasing GA content. The microscopic appearance of the rapture zones of the finite-span testing mainly indicated intrafibre failure for the GA-modified fibres. It was concluded that cross-linking is likely to be the major reason for tensile strength loss of GA- and DMDHEU-modified wood. In terms of DMDHEU-modified wood, the incrustation of the cell wall by the resin and the reduction in pliability could play an additional role.

  • 33.
    Hao, Meng-Shu
    et al.
    Lund Univ.
    Jensen, Anna M.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT). Lund Univ.
    Boquist, Ann-Sofie
    Lund Univ.
    Liu, Yun-Jun
    Lund Univ ; Chinese Acad Agr Sci, Peoples R China.
    Rasmusson, Allan G.
    Lund Univ.
    The Ca2+-Regulation of the Mitochondrial External NADPH Dehydrogenase in Plants Is Controlled by Cytosolic pH2015Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, nr 9, e0139224Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    NADPH is a key reductant carrier that maintains internal redox and antioxidant status, and that links biosynthetic, catabolic and signalling pathways. Plants have a mitochondrial external NADPH oxidation pathway, which depends on Ca2+ and pH in vitro, but concentrations of Ca2+ needed are not known. We have determined the K-0.5(Ca2+) of the external NADPH dehydrogenase from Solanum tuberosum mitochondria and membranes of E. coli expressing Arabidopsis thaliana NDB1 over the physiological pH range using O-2 and decylubiquinone as electron acceptors. The K-0.5(Ca2+) of NADPH oxidation was generally higher than for NADH oxidation, and unlike the latter, it depended on pH. At pH 7.5, K-0.5(Ca2+) for NADPH oxidation was high (approximate to 100 mu M), yet 20-fold lower K-0.5(Ca2+) values were determined at pH 6.8. Lower K-0.5(Ca2+) values were observed with decylubiquinone than with O-2 as terminal electron acceptor. NADPH oxidation responded to changes in Ca2+ concentrations more rapidly than NADH oxidation did. Thus, cytosolic acidification is an important activator of external NADPH oxidation, by decreasing the Ca2+-requirements for NDB1. The results are discussed in relation to the present knowledge on how whole cell NADPH redox homeostasis is affected in plants modified for the NDB1 gene.

  • 34.
    Blomqvist, Lars
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Sterley, Magdalena
    SP Technical Research Institute of Sweden.
    Sandberg, Dick
    Luleå University of Technology.
    Johansson, Jimmy
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    The effect of veneer modification on the bond-line strength in laminated veneer products2015Ingår i: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 11, nr 4, 43-49 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A major problem in the manufacture of three-dimensional laminated veneer products (LVP) isdamage due to stretching and/or buckling of the veneer. To reduce or eliminate this problem, veneerdensification or adding a strengthening layer to the veneer can be an alternative. To study how veneermodification influences the veneer-to-adhesive bond strength, three methods of modification werestudied in relation to an unmodified reference veneer: (1) densified veneer, (2) veneer pre-bonded withpaper and hot melt adhesive (HMA), (3) veneer pre-bonded with non-woven polypropylene (NW)fabric glued to the veneer (a) with a urea formaldehyde (UF) adhesive, (b) with a mixture of UF andpolyvinyl acetate (PVAc) adhesive, and (c) with a PVAc adhesive. Densification, pre-bonding withpaper, and NW with UF/PVAc adhesive mixture resulted in no or only a slight decrease in strength ofthe bond-line compared to the reference. NW glued with UF or PVAc adhesive showed a considerablereduction in the strength of the bond-line. The climatic cycling had no significant influence on the bondstrength.

  • 35.
    Mahnert, K-C
    et al.
    Norwegian Institute of Wood Technolgy, Norway ; Georg August University of Göttingen, Germany.
    Adamopoulos, Stergios
    Technological Educational Institute of Thessaly, Greece.
    Koch, G
    Thünen Institute of Wood Research, Germany.
    Militz, Holger
    Georg August University of Göttingen, Germany.
    UV-microspectrophotometry: A method to prove wood modification with MMF?2015Ingår i: International Wood Products Journal, ISSN 2042-6445, Vol. 6, nr 1, 27-30 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The modification of wood with methylolated melamine formaldehyde resin belongs to the group of impregnation modifications. In the course of this study, Koto sapwood samples were impregnated with methylolated melamine formaldehyde resin solutions in a full cell vacuum pressure process. The samples were cured at a maximum temperature of 120°C for 24 h. To characterise the modification, the solution uptake and weight percent gain of the samples were calculated. The fixation of the melamine as parameter for the degree of curing was examined by C/N analysis. Areal UV-microspectrophotometry scans of ultra-thin transverse sections of an untreated control and samples impregnated with methylolated melamine formaldehyde resin at 240 nm were recorded. Additionally, photometric point measurements with a spot size of 1 μm−2 in the range 230 and 350 nm were conducted. UV-microspectrophotometry was proven as suitable technique for the quantitative analysis of wood modified with methylolated melamine formaldehyde resin.

  • 36.
    Bastani, Alireza
    et al.
    Georg-August-University Göttingen, Germany.
    Adamopoulos, Stergios
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för skog och träteknik (SOT).
    Militz, Holger
    Georg-August-University Göttingen, Germany.
    Water uptake and wetting behaviour of furfurylated, N-methylol melamine modified and heat-treated wood2015Ingår i: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 73, nr 5, 627-634 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study reports on the water uptake (WU) and wetting properties of different modified wood materials; furfurylated and N-methylol melamine (NMM) modified Scots pine, and heat-treated (Vacu3 method) Scots pine and beech. All modifications caused a substantial reduction in WU in the longitudinal, tangential and radial directions both after short (24 h) and long contact times (168, 336 h) with a saturated sponge. The water uptake coefficient (w t ) was reduced by approximately 71–89 % in furfurylated wood, with the higher weight percent gain (WPG) providing a slightly greater reduction. The reduction in WU was not found to depend on the NMM solid content. The NMM treatment had the maximum effect on the reduction of tangential w t by 80–84 % and was much smaller in the longitudinal direction (31–68 %). The treatment temperature of 195 °C gave lower WU values than treatment at 210 °C, and the only exception was the radial direction of Scots pine. The longitudinal w t of heat-treated beech represented the highest reduction by 81–89 %, while radial w t was less affected in both species. Sessile drop apparent contact angles for water and diidomethane and corresponding surface energies on planed tangential and radial wood surfaces revealed an increased hydrophobicity and reduced polarity of modified wood. Furfurylated and NMM modified tangential surfaces had a higher increase of apparent contact angles than the radial surfaces but this was not observed in the case of heat treatment. Heat-treated wood showed reduced wetting of surfaces only with water. Apparent contact angles did neither differ with treatment temperature nor with the NMM resin load. The disperse component of surface energy was slightly increased by 20 % maximum in modified wood, while the polar components showed a dramatic decrease by −30 to −90 % with no major differences among treatments and intensities, and between surfaces. The results provide a better understanding of the hygroscopic behaviour of modified wood, which might be useful to predict its adhesion with various polymers such as glues, coatings and paints.

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